This invention relates to a technique that is applied to a semiconductor device, especially to a semiconductor device having a base substrate that comprises flexible films.
As a suitable semiconductor device for a high-pin-count package, a semiconductor device having a BGA (BALL GRID ARRAY) structure has been developed. In this semiconductor device with a BGA structure, a semiconductor chip is mounted on a chip mount area of a main surface of a base substrate by using adhesive material and several bump electrodes are positioned in an array on the back side thereof that is opposite to said main surface of the base substrate.
The above-mentioned base substrate is provided in the form of the rigid resin substrate that consists of glass impregnated with, for example, an epoxy resin, a polyimide resin, a maleimide resin, etc. Electrode pads for wire connection are arranged in a peripheral area that surrounds the periphery of the chip mount area of the main surface of the base substrate, and several electrode pads for bump connection are arranged on the back of the base substrate. The bump electrodes comprise solder materials of, for example, a Pb—Sn composition, which fix and connect to the electrode pads for bump connection electrically and mechanically.
The above-described semiconductor chip comprises the structure mainly of a semiconductor substrate that includes, for example, monocrystal silicon. On the semiconductor chip, a logical circuit system, a storage circuit system or a mixture of these circuit systems are formed. And, several external terminals (bonding pads) are allocated to the main surface (element formation face) of the semiconductor chip. These external terminals are electrically connected through wires to electrode pads for wire connection arranged on the main surface of the base substrate.
The semiconductor chip, the wires, the electrode pads for wire connection, etc. are sealed in the resin sealing body formed on the main surface of the base substrate. The resin sealing body is formed by a method of transfer molding, which is suitable for mass production.
A semiconductor device of the BGA structure composed like this is mounted on the surface of a printed circuit board by melting connection of the bump electrodes onto the electrode pads formed on the surface of the printed circuit board.
NIKKEI electronics (Feb. 28, 1994, from the 111th page to the 117th page) published by NIKKEI BP, describes a semiconductor device having the above-described BGA structure.